I.U.D.'s used for the purpose of contraception are old in art, having been popularized by the development of Dr. Ernst Grafenberg's silver ring. Since that time, almost forty years ago, there have been many improvements in both the configuration and the material of the device as well as the efficiency and the public acceptance of the device. The configuration of the I.U.D.'s most frequently used today may be categorized generally as coils, loops, rings and bows, the best known examples being those devices developed by Margulies, lippes, Ota and Birnberg, respectively.
It has long been recognized that even though I.U.D.'s are safe, reliable and efficient, there are still several very important strucutral aspects that can be improved.
It has been also recognized that although the I.U.D. must be readily removable, if possible without surgical interference, yet it must be capable of resisting expulsion caused by the involuntary uterine contractions exhibited by the fundus muscle. These are, of course, diametrically opposite conditions, but which must nevertheless be met for the I.U.D to be effective.
It has also been recognized that the I.U.D. for proper reliability must have a good contact with the walls of the uterus, which belief lead to the inflatable types such as described in my U.S. Pat. No. 3,933,153 and 3,996,932.
It has been also recognized in my aforementioned patents that contact with the inner walls of the uterus is desirable rather at a plurality of smaller regions than at large surfaces in order to minimize irritations of the inner wall of the uterus and to avoid blockage of the menstrual flow. At the same time an I.U.D. answering the above requirements must retain the last mentioned beneficial properties even under the expulsionary effects of the fundus and in addition assumes a shape which laterally increases its size with respect to the cervix under the last mentioned conditions and reliably prevents thereby its expulsion.
The I.U.D. devices described in my aforementioned patents have superior qualities and improved physiological properties, however, due to their inflatable character, they are sensitive to manufacturing conditions and their insertion requires a rather elaborate inserting device equipped with inflating needle.